The planet known for having the highest mountain and the deepest canyon in the solar system is Mars. Olympus Mons, the tallest volcano and mountain on Mars, reaches about 13.6 miles high, making it nearly three times the height of Mount Everest. Valles Marineris, the solar system's deepest canyon, stretches over 2,500 miles long and reaches depths of around 7 miles. These formidable geological features highlight Mars' unique landscape and have sparked interest in exploring the planet for potential past life and geological history.